OBJECTIVE: We launched a prospective cranial ultrasound study at the Department of Obstetrics and Gynaecology of the University of Giessen. In this study we examined the incidence and severity of brain damage in neonates and related them to various obstetrical risk factors. STUDY DESIGN: More than 90% of all neonates born between 1984 and 1988 were included in the study (n = 5286) and were screened by ultrasound for cerebral abnormalities on 5-8 days post-partum. The relation between the incidence of peri/intraventricular haemorrhages (PIVH) and obstetrical risk factors were analyzed by contingency tables. RESULTS: The most frequent abnormality was PIVH (3.6%) of various degrees (grade I-III). Periventricular leucomalacia, porencephalia, subarachnoidal haemorrhages, and hydrocephali were rare (< or = 0.2%). The incidence of PIVH increased progressively with decreasing gestational age, e.g. from 1.6% at 38-43 weeks up to 50.0% at 24-30 weeks of gestation. A large percentage of babies with PIVH were clinically normal. In immature neonates there was a close inverse relationship between Apgar score at 1, 5 and 10 min and both incidence and severity of PIVH. This was in contrast to findings in mature neonates where a marked increase in the incidence of PIVH was found only with Apgar scores as low as 0-4 points. The relation between the incidence of PIVH and both cardiotocography and arterial cord blood pH was poor, independent of the gestational age. The incidence of PIVH was increased in growth retarded fetuses (pH < or = 7.29), premature rupture of membranes, fever sub partu and gestosis. It is interesting to note that in mature fetuses there was no difference in the incidence of PIVH between vaginally delivered (0.8%) and sectioned breech presentations (2.1%). In preterms at 35-37 weeks with prolonged labour and secondary cesarean section, the incidence of PIVH was very high (11.2%). CONCLUSION: From the present study we conclude that the incidence of PIVH especially in immature neonates is highly associated with low Apgar scores at birth. Since the Apgar score reflects the clinical condition and the degree of circulatory centralisation of neonates that is influenced by various ante- and intranatal risk factors, a protective obstetrical management is necessary to reduce the incidence of PIVH in neonates.